A number of programmable sewing machines have been devised and are currently available on the market today, one of which is the Model AMS-206A by Juki. Sewing machines of this type offer a number of advantages. For instance, sewing operations are controlled by computer software. More particularly, sewing patterns stored in computer memory and accessible by the software are used to control the movement of a presser foot assembly which engages and moves the stitchable material relative to the sewing needle to produce a desired, preselected pattern. Consequently, programmable sewing machines are commonly used in commercial, high production applications.
One of the many uses of programmable sewing machines is for sewing a selected patterned design around an opening in stitchable material to produce a buttonhole or other desirable design. Although no presently known programmable sewing machine incorporates a punch or other assembly for removing stitchable material, there are separate punching machines commercially available. Utilizing a separate punching machine with a programmable sewing machine, however, is disadvantageous in that not only is more space required, but the additional punching machine increases both the initial capital expenditure and subsequent maintenance costs. Furthermore, the capabilities of the programmable sewing machine may not be fully realized in this type of configuration.
Unlike programmable sewing machines, there are non-programmable sewing machines commercially available which integrate a punch assembly with sewing operations. U.S. Pat. Nos. 345,663 to Blodgett issued Jul. 20 1886; 1,225,247 to Hill, issued May 8, 1917; 1,650,588 to Allen, issued Nov. 29, 1927; and 2,515,740 to Smith, et al., issued Jul. 18, 1950 are representative of this type of machine. Although configurations of this type alleviate the need for a separate punching machine, a number of disadvantages are evident based primarily upon the complex manner in which the drive assemblies for sewing and punching operations are typically coupled and integrated. For instance, maintenance costs for these machines are increased since they are both more difficult to repair and since there are additional parts which are subject to wear and/or breakage. Moreover, the complex integration of both operations effectively limits the use of these machines to one function--that of sewing buttonholes. Relatedly, in order to possibly limit the increase in size necessitated by adding the punching assembly, machines of this type commonly perform punching and sewing operations in the same general area, that being the cylinder bed.
Although welting machines cannot be used for buttonhole sewing operations, such machines do typically perform a material cutting operation outside the cylinder bed. Welting machines are used to form welts for pockets on coats and other articles of clothing. A typical welting machine initially places two end cuts on the material to define the ends of the pocket by utilizing the upward movement of knives positioned outside the cylinder bed. The machine then transfers the material to the cylinder bed to align one of the end cuts with a downwardly reciprocating knife and a sewing needle which are positioned in close proximity to each other. As the material is advanced, the reciprocating knife cuts the material toward the second end cut while the trailing needle sews the welt. Welting machines, however, are generally limited to a single function due to the manner in which the cutting and sewing operations are integrated. Moreover, although there is a material cutting operation performed outside the cylinder bed, no amount of material is removed since the upwardly reciprocating knife merely separates the fibers forming the material.
One apparatus which addresses the need for a detachable punch-type assembly is U.S. Pat. No. 2,954,001 to Luxenburg, issued Sep. 27, 1960, which generally discloses an automatic eyelet attachment. The eyelet attachment, which includes a punch and presser foot, is positioned on a standard non-programmable sewing machine in place of the original presser foot. When sewing an eyelet, the punch penetrates and spreads fibers but does not actually remove any substantial amount of material. With the punch remaining in the material, the needle stitches a pattern therearound to form the eyelet. A disadvantage of a punch of this type is that the material tends to pucker when the punch is inserted, resulting in a product which may be aesthetically displeasing. Consequently, this puts a realistic limitation on the size of the eyelet that can be produced since larger punches of this type will only increase puckering. Moreover, the punching operation takes place in the sewing area or cylinder bed since the needle actually sews around the punch while in the material to form the eyelet. Furthermore, positioning this eyelet attachment on a programmable sewing machine which automatically advances the stitchable material by movement of the presser foot assembly would not appear to provide an operational system. More particularly, the presser foot assembly of a programmable sewing machine moves during sewing operations which would introduce a problem since the punch disclosed by Luxenburg, which is attached to the presser foot, remains in the material while the eyelet is sewn.
In some applications, it may be desirable to not only remove material portions of stitchable materials with a punching-type assembly, but to dispose of such removed portions as well. For instance, fibers or strands of material may be generated during the removal operations and such materials may collect and adversely affect the performance of the sewing machine. Moreover, in high production applications the removed portions, if not properly disposed of, may also present a number of problems.
A single action pneumatic cylinder punch is available from BIMBA which utilizes one type of a disposal system. The BIMBA cylinder is used to punch relatively heavy materials such as plastics. In this regard, the cutting head is hollow and is connected to a hollow shaft of the cylinder. The cylinder shaft is attached to the piston which has a small orifice therein which is aligned with the hollow portion of the cylinder shaft. Consequently, when air is applied to drive the piston, cylinder shaft, and cutting head in a downward direction, a comparatively small air flow simultaneously passe through the orifice in the piston and through the hollow portion of the shaft and cutting head such that the removed portion, when formed, will be displaced from the hollow cutting head. Therefore, air is actually applied to the portion to be punched prior to the removal of such portion and actually even prior to the cutting head contacting such portion.